Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction
The γ-decay of resonances forming resonance-like structure have been investigated in the ³⁶S(pγ)³⁷Cl reaction. The decay schemes have been established for the first time. The branching ratios and probabilities of direct γ-transitions have been determined. The assumption that these resonances bel...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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irk-123456789-805072015-04-19T03:02:52Z Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction Kachan, A.S. Vodin, A.N. Kurguz, I.V. Lepyoshkina, O.A. Trotsenko, S.A. Ushakov, I.V Ядерная физика и элементарные частицы The γ-decay of resonances forming resonance-like structure have been investigated in the ³⁶S(pγ)³⁷Cl reaction. The decay schemes have been established for the first time. The branching ratios and probabilities of direct γ-transitions have been determined. The assumption that these resonances belong basically to the states of the M1 resonance on the first excited state in ³⁷Cl has been stated. Position of the M1 resonance has been explained with the account of pairing forces. У реакції ³⁶S(pγ)³⁷Cl досліджено γ- розпад резонансів, що утворюють резонансноподібну структуру. Уперше побудовано схеми розпаду, встановлено коефіцієнти гілкування та імовірності прямих γ-переходів. Висловлено припущення про те, що ці резонанси належать в основному станам М1-резонансу на першому збудженому стані ядра ³⁷Cl. Положення М1-резонанса пояснюється з урахуванням сил спарювання. В реакции ³⁶S(pγ)³⁷Cl исследован γ-распад резонансов, образующих резонансно-подобную структуру. Впервые установлены схемы распада, определены коэффициенты ветвления и вероятности первичных γ-переходов. Высказано предположение о том, что эти резонансы принадлежат в основном состояниям М1-резонанса на первом возбужденном состоянии ядра ³⁷Cl. Положение М1-резонанса объясняется с учетом сил спаривания. 2004 Article Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction / A.S. Kachan, A.N. Vodin, I.V. Kurguz, O.A. Lepyoshkina, S.A. Trotsenko, I.V. Ushakov // Вопросы атомной науки и техники. — 2004. — № 5. — С. 39-42. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 24.30.G, 13.40.H, 21.60.E http://dspace.nbuv.gov.ua/handle/123456789/80507 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
| topic |
Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы |
| spellingShingle |
Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы Kachan, A.S. Vodin, A.N. Kurguz, I.V. Lepyoshkina, O.A. Trotsenko, S.A. Ushakov, I.V Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction Вопросы атомной науки и техники |
| description |
The γ-decay of resonances forming resonance-like structure have been investigated in the ³⁶S(pγ)³⁷Cl reaction. The
decay schemes have been established for the first time. The branching ratios and probabilities of direct γ-transitions
have been determined. The assumption that these resonances belong basically to the states of the M1 resonance on the
first excited state in ³⁷Cl has been stated. Position of the M1 resonance has been explained with the account of pairing
forces. |
| format |
Article |
| author |
Kachan, A.S. Vodin, A.N. Kurguz, I.V. Lepyoshkina, O.A. Trotsenko, S.A. Ushakov, I.V |
| author_facet |
Kachan, A.S. Vodin, A.N. Kurguz, I.V. Lepyoshkina, O.A. Trotsenko, S.A. Ushakov, I.V |
| author_sort |
Kachan, A.S. |
| title |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction |
| title_short |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction |
| title_full |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction |
| title_fullStr |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction |
| title_full_unstemmed |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction |
| title_sort |
resonance-like structure in ³⁶s(pγ)³⁷cl reaction |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2004 |
| topic_facet |
Ядерная физика и элементарные частицы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/80507 |
| citation_txt |
Resonance-like structure in ³⁶S(pγ)³⁷Cl reaction / A.S. Kachan, A.N. Vodin, I.V. Kurguz, O.A. Lepyoshkina, S.A. Trotsenko, I.V. Ushakov // Вопросы атомной науки и техники. — 2004. — № 5. — С. 39-42. — Бібліогр.: 9 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT kachanas resonancelikestructurein36spg37clreaction AT vodinan resonancelikestructurein36spg37clreaction AT kurguziv resonancelikestructurein36spg37clreaction AT lepyoshkinaoa resonancelikestructurein36spg37clreaction AT trotsenkosa resonancelikestructurein36spg37clreaction AT ushakoviv resonancelikestructurein36spg37clreaction |
| first_indexed |
2025-07-06T04:31:10Z |
| last_indexed |
2025-07-06T04:31:10Z |
| _version_ |
1836870555070889984 |
| fulltext |
RESONANCE-LIKE STRUCTURE IN 36S(pγ)37Cl REACTION
A.S. Kachan, A.N. Vodin, I.V. Kurguz, O.A. Lepyoshkina, S.A. Trotsenko, I.V. Ushakov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
e-mail:kachan@kipt.kharkov.ua
The γ-decay of resonances forming resonance-like structure have been investigated in the 36S(pγ)37Cl reaction. The
decay schemes have been established for the first time. The branching ratios and probabilities of direct γ-transitions
have been determined. The assumption that these resonances belong basically to the states of the M1 resonance on the
first excited state in 37Cl has been stated. Position of the M1 resonance has been explained with the account of pairing
forces.
PACS: 24.30.G, 13.40.H, 21.60.E
1. INTRODUCTION
In our previous works [1-3], studying the γ-decay of
resonance-like structures (RLS) in the proton radiation
capture reaction by 21Ne, 25Mg, 29Si and 34S, we have
found out the new phenomenon connected with exis-
tence of triplet pairing between odd neutron and proton
taking place on the same orbit. The position of the cen-
tre of gravity (c.g.) of the magnetic dipole resonance
(MDR) in odd-odd nuclei 4N + np was found to be on 3
MeV below on excitation energy than in even-even nu-
clei 4N. In the same works a model for explanation of
this fact was offered. From the model it follows that odd
nuclei of sd-shell can be divided into two groups de-
pending on in what sub-shell there is an odd particle –
in d5/2-or d3/2-state. In the first case the position of c.g. of
МDR will be in the range of excitation energy about 5
…6 MeV since it is determined only by energy of spin-
orbital splitting. In the second case – at excitation ener-
gy approximately 9-10 MeV since in this case (nn)- or
(pp)- pairs from d5/2-subshell will be involved in forma-
tion of MDR.
New experimental data on position, fine structure
and total strength of MDR in odd nuclei are necessary
for confirmation and the further development of model
approximations of the nature of МDR and mechanisms
of its excitation. In the present work the cycle of mea-
surements connected with identification and determina-
tion of RLS position, observed in the 36S(pγ)37Cl reac-
tion is described.
2. EXPERIMENTAL PROCEDURE
The experiments were performed with the proton
beam from the 3 MeV Van de Graaf accelerator at the
Nuclear Spectroscopy Laboratory of NSC “KhIPT”. A
target of approximately 2 keV thickness at Ep = 2 MeV
consisting of Ag2S (81.1 % 36S) was used [4]. A beam
current of 15 µA was maintained during the experi-
ments.
The γ-radiation was detected with a 70 cm3 Ge(Li)-
detector (total width at half maximum was equal to
3.1 keV at 1.332 MeV) coupled to a 4096 channel ana-
lyzer. The detector was at an angle θlab = 55° in relation
to a proton beam. The Ge(Li)-detector efficiency was
determined with calibrated standard sources and using
relative γ-ray intensities in the 27Al(pγ)28Si reaction [5].
The angular distributions of γ-rays, arising from the
decay of resonance states in 37Cl, were measured at an-
gles 0°, 30°, 45°, 60° and 90° concerning a proton beam
direction. As a radiation monitor a current integrator
and additionally a spectrometer on the basis of
a ∅ 150 × 100 mm NаJ(Тl) crystal were used. This de-
tector was used to obtain a yield curve of the 36S(pγ)37Cl
reaction as a function of proton energy.
3. RESULTS OF MEASUREMENTS
3.1. EXCITATION FUNCTION
In the present investigations the excitation function of
the 36S(pγ)37Cl reaction was measured in the proton energy
region Ер = 2000…2400 keV. Measurements were carried
out with ∆Ер = 0.8 keV. The yield curve of the 36S(pγ)37Cl
reaction registered by the NaJ(Тl)-detector at an angle θ
lab = 55° with respect to a proton beam direction is repre-
sented in Fig. 1. Measurements were done with the Е
γ > 6.13 MeV discrimination threshold for energy of γ-
rays.
The experimentally observable widths of resonances
indicated in Fig. 1 are equal approximately to 2.1 keV
and are limited by a finite thickness of a target and ener-
gy scatter in a proton beam. The results obtained at the
analysis of the excitation function of the 36S(pγ)37Cl re-
action are represented in detail in [6].
3.2. RESONANCE STRENGTHS AND γ-WIDTHS
For determination of the absolute yield of γ-rays from
the 36S(pγ)37Cl reaction the comparison of researched res-
onances with the resonance at Ер = 1887 keV was carried
out. The strength for the last one was equal to [7]:
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2004, № 5.
Series: Nuclear Physics Investigations (44), p. 39-42. 39
eV331)12( γp ±=+=
Г
ГГ
JS , (1)
2000 2100 2200 2300 2400
0
20000
40000
E
p
, кeV
-2
39
2
-2
29
5
-2
22
8
-2
16
5-2
12
6
-2
08
0
-2
05
8
Nγ
-2
03
7
Fig. 1. The excitation function of the 36S(pγ)37Cl reaction in the energy region Ер = 2000…2400 keV
Spectroscopic data on resonance levels and probabilities of M1 transitions in 37Cl
Ep, keV MeV,**
fi EE → ππ → fi JJ S, eV b, % а2 ± ∆а2 а4 ± ∆а4 a6 ± ∆а6 δ(∆δ) B(M1)↑,
2
Nμ
2037 10.368 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 40(2) 25
65
0.25±0.12
-0.40±0.10
-0.14±0.12
0.05±0.10
-0.01±0.13
-0.11±0.09
0.0(1)
0.26(15)
0.21(4)
1.7(5)
2080 10.410 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 20(2) 93
3
0.38±0.09
-
-0.05±0.08
-
0.06±0.09
-
-0.17(15)
(0)
0.36(1)
0.04(1)
2126 10.455 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 23(3) 61
21
0.42±0.15
-0.32±0.12
0.41±0.15
-0.11±0.12
0.14±0.17
-0.03±0.10
-0.7(5)
0.3(2)
0.13(4)
0.21(6)
2165 10.492 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 23(3) 34
31
0.01±0.11
-0.12±0.12
-0.04±0.12
0.09±0.13
0.08±0.13
0.07±0.12
0.26(15)
-0.28(20)
0.14(4)
0.44(12)
2228 10.554 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 22(2) 55
28
0.09±0.11
-0.35±0.13
0.12±0.13
0.12±0.12
0.15±0.14
-0.11±0.12
0.0(1)
0.0(1)
0.22(2)
0.39(4)
2392 10.713 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 27(3) 39
61
-0.09±0.14
-0.39±0.14
-0.09±0.15
0.04±0.13
0.12±0.16
0.010.14
0.46(20)
0.27(20)
0.16(4)
0.95(28)
2428 10.745 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 19(2) 70
20
0.29±0.12
-0.23±0.26
0.07±0.12
0.24±0.28
0.13±0.14
-0.21±0.30
-0.21(15)
0.57(30)
0.18(3)
0.26(5)
2459 10.780 → 0
→ 1.727
3/2+ → 3/2+
→ 1/2+ 25(3) 15
75
-0.04±0.11
-0.44±0.12
0.35±0.13
0.02±0.11
-0.10±0.12
-0.02±0.11
-0.07(10)
0.52(30)
0.06(1)
0.87(16)
where J – a spin of a resonance state, Гр, Гγ and Г – pro-
ton, radiation and total widths of a resonance. The S values
received for researched resonances are listed in the Table
(4 column). The evaluation of values of a radiation reso-
nance width was carried out in assumption that Гр >> Гγ.
3.3. RESONANCE DECAY SCHEMES
Based on balance of energy values and intensities of ob-
served γ-transitions the γ-decay schemes of investigated
resonances were defined in view of all known data on lev-
els of the 37Cl nucleus. The branching ratios b for re-
searched resonance levels are presented in the Table (5 col-
umn).
3.4. ANGULAR DISTRIBUTIONS OF γ-RAYS
The angular distributions of γ-rays were measured
for determination of quantum characteristics of the reso-
nances forming RLS. The function of angular correla-
tion W(θ) was searched as an expansion on even poly-
nomials of Legendre:
40
)),
)))
θ
θθθ
(cos
(cos(cos1((
66
44220
Pa
PaPaAW
+
+++=
(2)
where A0 is the normalization constant, the coefficients
a2 and a4 depend on an angular moment of initial and fi-
nal states and a parameter δ. The a2 and a4 coefficients,
found using the method of least squares, were compared
to their theoretical values for various hypotheses about a
spin J of a resonance level and appropriate δ value with
the help of criterion 2χ . The combination of J and δ
was rejected if the obtained value 2
min
2 χχ ≡ exceeded
probable 0.1%-limit. The defined thus a2 and a4 coeffi-
cients in the function of angular distribution of γ-rays
and δ values, appropriate to them, are represented in the
Table (6-9 columns). The corrections which take into
account a final solid angle of the Ge(Li)-detector are
brought into results of measurements. The indicated er-
rors are standard deviations.
Probable values of Jπ for the most intensive reso-
nances forming RLS are given in the Table (3 column).
The values of parity are attributed to a state on the basis
of comparison of probabilities of electromagnetic transi-
tions with various multipolarities taking in consideration
recommended upper limits for probabilities of electro-
magnetic γ-transitions in nuclei with А < 44 [9].
The experimental values of probabilities of γ-tran-
sitions B(M1)↑ between resonances and bound states of
37Cl based on obtained data were determined. Values of
B(M1)↑ were calculated by the formula:
2
3 N65,21)1( µ⋅↑ =
γЕ
SbMB , (3)
where Eγ – energy of γ-transition.
4. DISCUSSION
The joint analysis of data in [6, 8, 9] and experimen-
tal results received has allowed to identify resonance-
like structure in 37Cl (Fig. 2), similar to that observed in
35Cl [2]. The estimation of the upper limit of B(M1) is
given on Figs. 2 a, b for states at which all quantum
characteristics are not known. These values do not ex-
ceed 0,05 2
Nµ (a “background” level for transitions to the
ground state) and 0,5 2
Nµ (a “background” level for transi-
tions to the first excited state).
9 10
0
20
40
9 10
0,0
0,2
0,4
9,0 9,5 10,0 10,5
0
1
2
36S(pγ )37Cl, S > 1 eV
a
S,
eV
B(
M
1)
↑,
µ
N
2 c
b
B(
M
1)
↑,
µ
N
2
r - 0 (3/2+)
r - 1,727 (1/2+)
E*, MeV
Fig. 2. The γ-decay of resonance-like structure in the 36S(pγ)37Cl reaction: a - strengths of resonances; b - re-
duced probabilities of γ-transitions from the ground state of 37Cl; c - reduced probabilities of γ-transitions from the
first excited state
41
The received distributions of probabilities for magnet-
ic dipole γ-transitions allow to conclude that resonances
forming RLS concern to the states of the M1-resonance
on the ground states (Fig. 2 a) and first excited (Fig. 2 b)
in 37Cl. The centre of gravity for MDR on the ground
state in 37Cl
∑∑=
k
k
k
kk MBMBEE )1(/)1(0 (4)
is equal to 12.8 MeV and it is located on energy of exci-
tation above on 1 MeV relative to 35Cl. It is possible to
explain the difference found in position of c.g. for MDR
in 35Cl and 37Cl nuclei by different connection of va-
lence particles in these nuclei.
The total strength of MDR on the ground state
∑=
k
kk
M
EW MBES )1(1
(5)
is equal to 12,8 MeV and it is also considerably differ
from that in 35Cl. It is connected with different number
of particles that take part in transition between spin - or-
bital partners. As a result of the carried out researches
MDR is identified on the ground and the first excited
states for the first time in 37Cl. Position of c.g., the total
strength and fine structure of MDR on the ground state
are determined. It is found to be in the excitation energy
expected for nuclei with closed d5/2-subshell.
This experimental fact is evidence of that nn or pp-
pair from d5/2-subshell in 37Cl takes part in formation of
the M1-resonance, therefore position of the centre of the
M1-resonance in this nucleus is influenced with value of
nn (pp) pairing in this sub-shell. The discrepancy in po-
sition of c.g and the total strength of the M1-resonance
is found in 35Cl and 37Cl nuclei and for explanation of
that the further researches are required.
REFERENCES
1. A.S. Kachan, B.A. Nemashkalo, V.E. Stor-
izhko. M1-resonance in sd-shell // Yad. Fhys. 1989,
v. 49, № 2, p. 367-370 (in Russian).
2. A.S. Kachan, A.N. Vodin, V.M. Mishchenko,
R.P. Slabospitsky. Fine structure of M1-resonance in
35Cl nucleus // Yad. Fhys. 1996, v. 59, p. 775-780 (in
Russian).
3. A.S. Kachan, A.N. Vodin,
V.M. Mishchenko, R.P. Slabospitsky. M1-reso-
nance in odd-A nuclei sd-shell // Izvestiya RAN,
Ser. phys. 2001, v. 65, № 5, p. 682-686 (in Rus-
sian).
4. D.D. Watson. Simple method for making
sulfur target // Rev. Sci. Inst. 1966, v. 37, p. 1605-
1606.
5. A. Anttila, J. Keinonen, M. Hauntala and
I. Fors-blom. Use of the 27Al(pγ)28Si kev resonance
asa γ-ray intensety standart // NIM. 1977, v. 147,
p. 501-505.
6. A.N. Vodin, A.S. Kachan,
V.M. Mishchenko, R.P. Slabospitsky. Gamma-de-
cay of resonance-like structure in 36S(pγ)37Cl reac-
tion // Izvestiya RAN, Ser. phys. 1996, v. 60, № 11,
p. 197-205 (in Russian).
7. A.N. Vodin, A.S. Kachan,
V.M. Mishchenko. f7/2 Isobaric analogue reso-
nance’s in odd-A nuclei 1d2s-shell // Izvestiya
RAN, Ser. phys. 2002, v. 66, № 1, p. 40-47 (in Rus-
sian).
8. P.M. Endt and C. Van der Leun. Energy lev-
els of nuclei A < 44 // Nucl. Phys. A. 1990, v. 521,
p. 1 - 873.
9. Yu.P. Іevlev, А.А. Koval’, Е.G. Kopanets et
al. Resonances in 36S(pγ)37Cl reaction // Ukraine
Physics Journal. 1967, v. 12, № 5, p. 747-753 (in
Russian).
РЕЗОНАНСНО-ПОДОБНАЯ СТРУКТУРА В РЕАКЦИИ 36S(pγ)37Cl
A.С. Kaчaн, А.Н. Водин, И.B. Kургуз, О.А. Лепешкина, С.А. Троценко, И.В. Ушаков
В реакции 36S(pγ)37Cl исследован γ-распад резонансов, образующих резонансно-подобную структуру. Впер-
вые установлены схемы распада, определены коэффициенты ветвления и вероятности первичных γ-переходов.
Высказано предположение о том, что эти резонансы принадлежат в основном состояниям М1-резонанса на пер-
вом возбужденном состоянии ядра 37Cl. Положение М1-резонанса объясняется с учетом сил спаривания.
РЕЗОНАНСНО-ПОДОБНА СТРУКТУРА В РЕАКЦІЇ 36S(pγ)37Cl
О.С. Kaчaн, О.М. Водін, І.В. Kургуз, О.О. Лепешкіна, С.О. Троценко, І.В. Ушаков
У реакції 36S(pγ)37Cl досліджено γ- розпад резонансів, що утворюють резонансноподібну структуру. Уперше
побудовано схеми розпаду, встановлено коефіцієнти гілкування та імовірності прямих γ-переходів.
Висловлено припущення про те, що ці резонанси належать в основному станам М1-резонансу на першому
збудженому стані ядра 37Cl. Положення М1-резонанса пояснюється з урахуванням сил спарювання.
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
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